The known stereoscopic arrangements are based on two separate microscopic beam paths for respective eyes of the viewer. The conventional arrangements are the Greenough type and the Galilei type. Both types have the disadvantage which is the limitation of microscopic resolution so that apertures greater than 0.1 are possible only with substantial complexity. This comes about because large working distances are desired in stereo arrangements and since, for conventional arrangements, only limited aperture space is present because of the following: the required angle for the stereo viewing, the two separate beam paths and the frame parts of the two beam paths with manipulable dimensioning.
It is further known to insert half diaphragms in the form of polarization filters in the condenser of a single-objective microscope in order to obtain a stereoscopic effect. The polarization directions of the polarization filters are mutually perpendicular and correspondingly orientated polarization filters must be provided in the two tubes. In this connection, reference can be made to the xe2x80x9cJournal of Microscopyxe2x80x9d, volume 153, February 1989, pages 181 to 186.
Published German patent application 4,311,603 discloses a stereomicroscope having a high magnification wherein an object translator is provided in the beam path on the object side of a single-objective light microscope in the object plane. A beam switchover device is mounted in the beam path on the image side. Disadvantageous is here the object translator because the movement of the translator can lead to vibrations of the entire microscope, especially for objects having a large mass.
U.S. Pat. Nos. 4,561,731 and 4,806,776 disclose that a pseudo stereoscopic effect can be generated with the aid of a so-called differential polarization illumination. For the illumination, two separate light sources are provided and polarizers are mounted downstream thereof for generating different polarization directions.
U.S. Pat. No. 4,561,731 shows in FIG. 10 thereof and in the description corresponding thereto that a proper stereoscopic image can be generated in that polarizers are mounted in the light path of the oculars and a double refracting plate is mounted between objective and object. The single illuminating beam path is alternately polarized differently.
A similar arrangement is described in PCT patent publication WO 94/02872. Here too, two light sources and two beam paths are utilized.
This also applies to a surgical microscope disclosed in published German patent application DD-A5 290,278. Two illuminating systems lying diametrically opposite to each other are inclined to the optical axis and the image viewed in the right ocular is assigned to the first illuminating system and the image viewed with the left ocular is assigned to the second illuminating system.
A method for generating stereoscopic images of an object is described in U.S. Pat. No. 5,835,264 incorporated herein by reference. This method includes the steps of illuminating an object with an illuminating beam; masking the illuminating beam to generate a first component beam to illuminate the object at a first angle and provide a first image of the object to a first viewing eye; again masking the illuminating beam to generate a second component beam to illuminate the object at a second angle and to provide a second image of the object to a second viewing eye; and, alternately repeating the last two steps at a frequency above the flicker frequency of the human eye.
The arrangement for carrying out the above method includes a beam generating device for alternately generating first and second illuminating beam components which illuminate the object via illuminating optics at respectively different angles to produce respective images of the object. A directing device alternately directs the images to the left and right eyes of a viewer at a frequency above the flicker frequency of the human eye.
In view of the above, it is an object of the invention to supplement the embodiments described in the above-identified application with further advantageous embodiments and to optimally configure the entire microscopic arrangement with respect to resolution and depth of field as well as with respect to stereo impression.
The stereoscopic image of a self-luminous object such as a microscopic fluorescent object is especially advantageously generated in that the exit pupil of the objective is sectioned and is alternately supplied in a clocked manner to the left and right eyes at a frequency above the flicker frequency. It is advantageous to section the exit pupil into two lunes having respective centroids which are so adjustable that viewing of the object at a variable stereo angle takes place while, simultaneously, the viewing aperture remains utilized to a maximum. In this way, a high microscopic resolution is achieved. In this method, transilluminated objects and incident-light illuminated objects can be viewed. Pupil sectioning takes place in one embodiment via a DMD mirror close to the exit pupil (DMD=Digital Micromirror Devices). Digital micromirror devices comprise a plurality of micromirrors having angle positions which can be electrostatically adjusted.
In a second embodiment, the pupil sectioning takes place in or close to the exit pupil via a light modulator such as a liquid crystal matrix. The image viewing takes places utilizing clocked image-recording and image-reproducing equipment, such as a video camera and monitor, or via clocked light modulators in the ocular beam path. The ocular beam paths can, however, also be clocked via a polarizing beam splitter having a switchable LCD cell.
In a third embodiment, the pupil sectioning takes place near the exit pupil via a high-resolution video camera. The image viewing takes place after a Fourier transformation of the two pupil images and clockwise reproduction for each eye via a monitor shutter or shutter spectacles.
It is further advantageous to mount diaphragms in or near the entry pupil of the microscope objective as well as in or near its exit pupil. The diaphragms are preferably adjustable and/or exchangeable.